Different sail configurations require different sheeting points -therefore; in order to achieve the best sail shape, you will need to move cars and/or shift tracks (when changing the sail size dramatically) as the sail demainds for proper trim...
Not the most desirable thing for a furled sail boat skipper... but there no way around it!
You might notice that some of the modern mass-produced boats come with a very long single tracks and remotely adjustable track cars... Not an ideal solution (again), but an attempt to cover as many of the options posible.
It is very common to see boats out on the bay carrying horrible sail trim ignoring the flailing sails' suffering with neither the crew or skipper bothering to adjust the sails...
Multiple sheet cars will ease the work required to shift from one track to another... Simply take-up the lazy sheet in on the inner track for closer trimming and switch the active shhet to the lazy side...
You can also carry two sets of sheets - one on each set of tracks/cars...